Israel's Supreme Court has overturned the government's landmark deal to begin pumping natural gas, handing a painful blow to Prime Minister Benjamin Netanyahu and a consortium of energy companies.

Sunday's decision gave parliament a year to amend the plan or the framework will be canceled.

Netanyahu has made the gas deal a centerpiece of his agenda, saying the discovery of large reserves would bring energy self-sufficiency and billions of dollars in tax revenues. Critics have said the deal gave excessively favorable terms to the government's corporate partners.

Resource-poor Israel announced the discovery of sizeable offshore natural gas deposits about five years ago, and a partnership of Israeli and U.S. companies, including Texas-based Noble Energy and Israel's Delek Group — have already begun extracting some reserves.